To date, various information appliances and home electric appliances, such as television receivers, video recording and playback devices, and audio-visual devices, have been developed and manufactured, and have been widely used in houses and other living spaces. Basically, such information devices are directly operated through user interfaces generally provided for the device main body, such as operation buttons and volume switches. Recently, however, almost all devices can be remotely operated using remote controllers.
For example, in the field of consumer electrical and electronic devices, such as home electrical products, “infrared remote controllers” using an AM modulation method as means for inputting user operation commands to the devices in a remote manner have been developed and have already been established.
Such a communication method using infrared light has advantages of low cost, low power consumption, substantially no legal restrictions in countries, and so forth. Elimination of hard-wired cabling also means that connectors for connecting cables are not necessary, leading to reduction in cost. There is no concern of mechanical exhaustion caused by inserting and removing connectors each time connection or disconnection occurs.
The communication method using infrared light, however, has a problem of directivity. Communication is not established unless a light-receiving unit of a receiver is set within the angle of view of a transmitter, which imposes a large limitation in use (see, for example, Patent Document 1). Further, the infrared communication method basically provides one-way communication, and has a problem that a transmission source is not able to receive a response from the other party and is not able to make a delivery confirmation.
It is possible to carry out two-way communication if both devices that are to perform communication are provided with an infrared transmission function and an infrared reception function. In infrared communication, however, due to the problem of directivity, users of both devices are inconvenienced by having to direct their devices to the other devices to perform transmission operations.
For example, a communication device that relays an infrared operation signal for an electronic device, which is emitted from a remote commander, to operate an electronic device located at a place where an infrared operation signal from a dedicated remote controller does not directly reach has been proposed (see, for example, Patent Document 2). This communication device extracts a pulse waveform component by removing a carrier component from the infrared operation signal received from the remote commander, and transmits the pulse waveform component through a network. The communication device also modulates an infrared carrier by the pulse waveform component, and transmits the modulated infrared carrier to the electronic device to be operated.
A remote operation system that is constructed with a simple device configuration in which no relay device or the like is used has been proposed (see, for example, Patent Document 3). A controller transmits capability information indicating the capability of input operations that can be performed by the controller to a device to be controlled, and the device to be controlled creates and returns remote-controller handling information for forming a user interface that can be realized within the range of the received capability information. The controller forms a user interface using the remote-controller handling information.
In the infrared communication method, however, due to the limited communication bandwidth, it is difficult to exchange a large amount of data such as moving pictures or still images, and the function of a terminal device for performing remote control is limited.
Further, a mobile-phone remote control system for allowing a reservation to be set in devices, such as home electric appliances, by using a mobile phone has been proposed (see, for example, Patent Document 4). According to this system, a remote controller receives a signal from a mobile phone, and optically transmits a remote control signal for remotely controlling a device to be controlled according to the received signal.
In the remote control system using a network, a mobile telephone network, or the like, a remote operation itself is possible; however, limitations on the communication bandwidth are still imposed, as in a standard remote control system, because the infrared communication method is adopted in the final stage in remote control.
[Patent Document 1]
    Japanese Unexamined Patent Application Publication No. 2002-165281[Patent Document 2]    Japanese Unexamined Patent Application Publication No. 2003-258464[Patent Document 3]    Japanese Unexamined Patent Application Publication No. 2003-143670[Patent Document 4]    Japanese Unexamined Patent Application Publication No. 11-284757